1. Field of the Invention
The present invention relates to an apparatus for treating a multifilament thread in a melt-spinning process.
2. Description of Related Art
When producing synthetic threads, a plurality of fine filament strands is extruded from a polymer melt in a melt-spinning process and then combined to form a multifilament thread after cooling down. In order to enable the subsequent guidance of the thread in further treatment steps, for example, for drawing the thread with the aid of godets, it is necessary to wet the thread. For this purpose, a spin finish fluid is applied to the thread. In order to ensure that all the filament strands disposed in the thread are wetted uniformly, the thread is interlaced with the aid of a compressed-air blast in an additional treatment step following the wetting step. This interlacing process, in other words, the so-called “pre-entangling,” results in a homogenized application of the spin finish fluid to the filament strands of the thread. At the same time, the filament strands are intermixed as a result of the interlacing process, which improves the cohesion of the filament strands disposed in the thread.
For carrying out the wetting and interlacing of the thread, an apparatus is disclosed in the prior art, for example, in EP 1 165 868 B1 or DE 10 2004 017210 A1, in which apparatus the treatment steps for wetting the thread and interlacing the same are carried out immediately one after the other in the thread path with a short interval in between. For this purpose, the devices for the application of spin finish fluid and the devices for interlacing the thread are disposed in a common housing. Immediately following the wetting process, the thread is guided with a spin finish fluid without further thread-guiding elements in a common treatment channel for subsequent interlacing. In this context, it is possible to achieve particularly compact apparatuses for treating a multifilament thread in several steps.
In the apparatus known from the prior art, it has now been observed that the interlacing of the filament strands within the thread produces dynamic effects that continue to act in the direction extending opposite to the thread path up to the wetting step and beyond the latter. However, such effects, which become particularly noticeable by way of twist effects appearing on the thread, can sometimes adversely affect the upstream treatment steps performed on the thread.